
/***************************************************************
* 
***************************************************************/
#include "crypt/serpent.h"
/*************************************************************/
/* This is an independent implementation of the encryption algorithm:   */
/*                                                                      */
/*         Serpent by Ross Anderson, Eli Biham and Lars Knudsen         */
/*                                                                      */
/* which is a candidate algorithm in the Advanced Encryption Standard   */
/* programme of the US National Institute of Standards and Technology.  */
/*                                                                      */
/* Copyright in this implementation is held by Dr B R Gladman but I     */
/* hereby give permission for its free direct or derivative use subject */
/* to acknowledgment of its origin and compliance with any conditions   */
/* that the originators of the algorithm place on its exploitation.     */
/*                                                                      */
/* Dr Brian Gladman (gladman@seven77.demon.co.uk) 14th January 1999     */

/* Timing data for Serpent (serpent.c)

Core timing without I/O endian conversion:

128 bit key:
Key Setup:    2402 cycles
Encrypt:       952 cycles =    26.9 mbits/sec
Decrypt:       914 cycles =    28.0 mbits/sec
Mean:          933 cycles =    27.4 mbits/sec

192 bit key:
Key Setup:    2449 cycles
Encrypt:       952 cycles =    26.9 mbits/sec
Decrypt:       914 cycles =    28.0 mbits/sec
Mean:          933 cycles =    27.4 mbits/sec

256 bit key:
Key Setup:    2349 cycles
Encrypt:       952 cycles =    26.9 mbits/sec
Decrypt:       914 cycles =    28.0 mbits/sec
Mean:          933 cycles =    27.4 mbits/sec

Full timing with I/O endian conversion:

128 bit key:
Key Setup:    2415 cycles
Encrypt:       985 cycles =    26.0 mbits/sec
Decrypt:       954 cycles =    26.8 mbits/sec
Mean:          970 cycles =    26.4 mbits/sec

192 bit key:
Key Setup:    2438 cycles
Encrypt:       985 cycles =    26.0 mbits/sec
Decrypt:       954 cycles =    26.8 mbits/sec
Mean:          970 cycles =    26.4 mbits/sec

256 bit key:
Key Setup:    2463 cycles
Encrypt:       985 cycles =    26.0 mbits/sec
Decrypt:       954 cycles =    26.8 mbits/sec
Mean:          970 cycles =    26.4 mbits/sec

*/

#define BLOCK_SWAP

#ifdef CORE_TIME
#  undef    BLOCK_SWAP
#endif

/* Partially optimised Serpent S Box boolean functions derived  */
/* using a recursive descent analyser but without a full search */
/* of all subtrees. This set of S boxes is the result of work   */
/* by Sam Simpson and Brian Gladman using the spare time on a   */
/* cluster of high capacity servers to search for S boxes with  */
/* this customised search engine.                               */
/*                                                              */
/* Copyright:   Dr B. R Gladman (gladman@seven77.demon.co.uk)   */
/*              and Sam Simpson (s.simpson@mia.co.uk)           */
/*              17th December 1998                              */
/*                                                              */
/* We hereby give permission for information in this file to be */
/* used freely subject only to acknowledgement of its origin    */

/* 15 terms */

#define sb0(a, b, c, d, e, f, g, h)    \
    t1 = a ^ d;     \
    t2 = a & d;     \
    t3 = c ^ t1;    \
    t6 = b & t1;    \
    t4 = b ^ t3;    \
    t10 = ~t3;      \
    h = t2 ^ t4;    \
    t7 = a ^ t6;    \
    t14 = ~t7;      \
    t8 = c | t7;    \
    t11 = t3 ^ t7;  \
    g = t4 ^ t8;    \
    t12 = h & t11;  \
    f = t10 ^ t12;  \
    e = t12 ^ t14

/* 15 terms */

#define ib0(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = a ^ b;     \
    t3 = t1 | t2;   \
    t4 = d ^ t3;    \
    t7 = d & t2;    \
    t5 = c ^ t4;    \
    t8 = t1 ^ t7;   \
    g = t2 ^ t5;    \
    t11 = a & t4;   \
    t9 = g & t8;    \
    t14 = t5 ^ t8;  \
    f = t4 ^ t9;    \
    t12 = t5 | f;   \
    h = t11 ^ t12;  \
    e = h ^ t14

/* 14 terms!  */

#define sb1(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = b ^ t1;    \
    t3 = a | t2;    \
    t4 = d | t2;    \
    t5 = c ^ t3;    \
    g = d ^ t5;     \
    t7 = b ^ t4;    \
    t8 = t2 ^ g;    \
    t9 = t5 & t7;   \
    h = t8 ^ t9;    \
    t11 = t5 ^ t7;  \
    f = h ^ t11;    \
    t13 = t8 & t11; \
    e = t5 ^ t13

/* 17 terms */

#define ib1(a, b, c, d, e, f, g, h)    \
    t1 = a ^ d;     \
    t2 = a & b;     \
    t3 = b ^ c;     \
    t4 = a ^ t3;    \
    t5 = b | d;     \
    t7 = c | t1;    \
    h = t4 ^ t5;    \
    t8 = b ^ t7;    \
    t11 = ~t2;      \
    t9 = t4 & t8;   \
    f = t1 ^ t9;    \
    t13 = t9 ^ t11; \
    t12 = h & f;    \
    g = t12 ^ t13;  \
    t15 = a & d;    \
    t16 = c ^ t13;  \
    e = t15 ^ t16

/* 16 terms */

#define sb2(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = b ^ d;     \
    t3 = c & t1;    \
    t13 = d | t1;   \
    e = t2 ^ t3;    \
    t5 = c ^ t1;    \
    t6 = c ^ e;     \
    t7 = b & t6;    \
    t10 = e | t5;   \
    h = t5 ^ t7;    \
    t9 = d | t7;    \
    t11 = t9 & t10; \
    t14 = t2 ^ h;   \
    g = a ^ t11;    \
    t15 = g ^ t13;  \
    f = t14 ^ t15

/* 16 terms */

#define ib2(a, b, c, d, e, f, g, h)    \
    t1 = b ^ d;     \
    t2 = ~t1;       \
    t3 = a ^ c;     \
    t4 = c ^ t1;    \
    t7 = a | t2;    \
    t5 = b & t4;    \
    t8 = d ^ t7;    \
    t11 = ~t4;      \
    e = t3 ^ t5;    \
    t9 = t3 | t8;   \
    t14 = d & t11;  \
    h = t1 ^ t9;    \
    t12 = e | h;    \
    f = t11 ^ t12;  \
    t15 = t3 ^ t12; \
    g = t14 ^ t15

/* 17 terms */

#define sb3(a, b, c, d, e, f, g, h)    \
    t1 = a ^ c;     \
    t2 = d ^ t1;    \
    t3 = a & t2;    \
    t4 = d ^ t3;    \
    t5 = b & t4;    \
    g = t2 ^ t5;    \
    t7 = a | g;     \
    t8 = b | d;     \
    t11 = a | d;    \
    t9 = t4 & t7;   \
    f = t8 ^ t9;    \
    t12 = b ^ t11;  \
    t13 = g ^ t9;   \
    t15 = t3 ^ t8;  \
    h = t12 ^ t13;  \
    t16 = c & t15;  \
    e = t12 ^ t16

/* 16 term solution that performs less well than 17 term one
   in my environment (PPro/PII)                                  

#define sb3(a,b,c,d,e,f,g,h)    \
    t1 = a ^ b;     \
    t2 = a & c;     \
    t3 = a | d;     \
    t4 = c ^ d;     \
    t5 = t1 & t3;   \
    t6 = t2 | t5;   \
    g = t4 ^ t6;    \
    t8 = b ^ t3;    \
    t9 = t6 ^ t8;   \
    t10 = t4 & t9;  \
    e = t1 ^ t10;   \
    t12 = g & e;    \
    f = t9 ^ t12;   \
    t14 = b | d;    \
    t15 = t4 ^ t12; \
    h = t14 ^ t15
*/

/* 17 terms */

#define ib3(a, b, c, d, e, f, g, h)    \
    t1 = b ^ c;     \
    t2 = b | c;     \
    t3 = a ^ c;     \
    t7 = a ^ d;     \
    t4 = t2 ^ t3;   \
    t5 = d | t4;    \
    t9 = t2 ^ t7;   \
    e = t1 ^ t5;    \
    t8 = t1 | t5;   \
    t11 = a & t4;   \
    g = t8 ^ t9;    \
    t12 = e | t9;   \
    f = t11 ^ t12;  \
    t14 = a & g;    \
    t15 = t2 ^ t14; \
    t16 = e & t15;  \
    h = t4 ^ t16

/* 15 terms */

#define sb4(a, b, c, d, e, f, g, h)    \
    t1 = a ^ d;     \
    t2 = d & t1;    \
    t3 = c ^ t2;    \
    t4 = b | t3;    \
    h = t1 ^ t4;    \
    t6 = ~b;        \
    t7 = t1 | t6;   \
    e = t3 ^ t7;    \
    t9 = a & e;     \
    t10 = t1 ^ t6;  \
    t11 = t4 & t10; \
    g = t9 ^ t11;   \
    t13 = a ^ t3;   \
    t14 = t10 & g;  \
    f = t13 ^ t14

/* 17 terms */

#define ib4(a, b, c, d, e, f, g, h)    \
    t1 = c ^ d;     \
    t2 = c | d;     \
    t3 = b ^ t2;    \
    t4 = a & t3;    \
    f = t1 ^ t4;    \
    t6 = a ^ d;     \
    t7 = b | d;     \
    t8 = t6 & t7;   \
    h = t3 ^ t8;    \
    t10 = ~a;       \
    t11 = c ^ h;    \
    t12 = t10 | t11;\
    e = t3 ^ t12;   \
    t14 = c | t4;   \
    t15 = t7 ^ t14; \
    t16 = h | t10;  \
    g = t15 ^ t16

/* 16 terms */

#define sb5(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = a ^ b;     \
    t3 = a ^ d;     \
    t4 = c ^ t1;    \
    t5 = t2 | t3;   \
    e = t4 ^ t5;    \
    t7 = d & e;     \
    t8 = t2 ^ e;    \
    t10 = t1 | e;   \
    f = t7 ^ t8;    \
    t11 = t2 | t7;  \
    t12 = t3 ^ t10; \
    t14 = b ^ t7;   \
    g = t11 ^ t12;  \
    t15 = f & t12;  \
    h = t14 ^ t15

/* 16 terms */

#define ib5(a, b, c, d, e, f, g, h)    \
    t1 = ~c;        \
    t2 = b & t1;    \
    t3 = d ^ t2;    \
    t4 = a & t3;    \
    t5 = b ^ t1;    \
    h = t4 ^ t5;    \
    t7 = b | h;     \
    t8 = a & t7;    \
    f = t3 ^ t8;    \
    t10 = a | d;    \
    t11 = t1 ^ t7;  \
    e = t10 ^ t11;  \
    t13 = a ^ c;    \
    t14 = b & t10;  \
    t15 = t4 | t13; \
    g = t14 ^ t15

/* 15 terms */

#define sb6(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = a ^ d;     \
    t3 = b ^ t2;    \
    t4 = t1 | t2;   \
    t5 = c ^ t4;    \
    f = b ^ t5;     \
    t13 = ~t5;      \
    t7 = t2 | f;    \
    t8 = d ^ t7;    \
    t9 = t5 & t8;   \
    g = t3 ^ t9;    \
    t11 = t5 ^ t8;  \
    e = g ^ t11;    \
    t14 = t3 & t11; \
    h = t13 ^ t14

/* 15 terms */

#define ib6(a, b, c, d, e, f, g, h)    \
    t1 = ~a;        \
    t2 = a ^ b;     \
    t3 = c ^ t2;    \
    t4 = c | t1;    \
    t5 = d ^ t4;    \
    t13 = d & t1;   \
    f = t3 ^ t5;    \
    t7 = t3 & t5;   \
    t8 = t2 ^ t7;   \
    t9 = b | t8;    \
    h = t5 ^ t9;    \
    t11 = b | h;    \
    e = t8 ^ t11;   \
    t14 = t3 ^ t11; \
    g = t13 ^ t14

/* 17 terms */

#define sb7(a, b, c, d, e, f, g, h)    \
    t1 = ~c;        \
    t2 = b ^ c;     \
    t3 = b | t1;    \
    t4 = d ^ t3;    \
    t5 = a & t4;    \
    t7 = a ^ d;     \
    h = t2 ^ t5;    \
    t8 = b ^ t5;    \
    t9 = t2 | t8;   \
    t11 = d & t3;   \
    f = t7 ^ t9;    \
    t12 = t5 ^ f;   \
    t15 = t1 | t4;  \
    t13 = h & t12;  \
    g = t11 ^ t13;  \
    t16 = t12 ^ g;  \
    e = t15 ^ t16

/* 17 terms */

#define ib7(a, b, c, d, e, f, g, h)    \
    t1 = a & b;     \
    t2 = a | b;     \
    t3 = c | t1;    \
    t4 = d & t2;    \
    h = t3 ^ t4;    \
    t6 = ~d;        \
    t7 = b ^ t4;    \
    t8 = h ^ t6;    \
    t11 = c ^ t7;   \
    t9 = t7 | t8;   \
    f = a ^ t9;     \
    t12 = d | f;    \
    e = t11 ^ t12;  \
    t14 = a & h;    \
    t15 = t3 ^ f;   \
    t16 = e ^ t14;  \
    g = t15 ^ t16

#define k_xor(r, a, b, c, d)    \
    a ^= l_key[4 * r +  8]; \
    b ^= l_key[4 * r +  9]; \
    c ^= l_key[4 * r + 10]; \
    d ^= l_key[4 * r + 11]

#define k_set(r, a, b, c, d)    \
    a = l_key[4 * r +  8];  \
    b = l_key[4 * r +  9];  \
    c = l_key[4 * r + 10];  \
    d = l_key[4 * r + 11]

#define k_get(r, a, b, c, d)    \
    l_key[4 * r +  8] = a;  \
    l_key[4 * r +  9] = b;  \
    l_key[4 * r + 10] = c;  \
    l_key[4 * r + 11] = d

/* the linear transformation and its inverse    */

#define rot(a, b, c, d)    \
    a = rotl(a, 13);    \
    c = rotl(c, 3);     \
    d ^= c ^ (a << 3);  \
    b ^= a ^ c;         \
    d = rotl(d, 7);     \
    b = rotl(b, 1);     \
    a ^= b ^ d;         \
    c ^= d ^ (b << 7);  \
    a = rotl(a, 5);     \
    c = rotl(c, 22)

#define irot(a, b, c, d)   \
    c = rotr(c, 22);    \
    a = rotr(a, 5);     \
    c ^= d ^ (b << 7);  \
    a ^= b ^ d;         \
    d = rotr(d, 7);     \
    b = rotr(b, 1);     \
    d ^= c ^ (a << 3);  \
    b ^= a ^ c;         \
    c = rotr(c, 3);     \
    a = rotr(a, 13)

/* initialise the key schedule from the user supplied key   */

u4byte* CSerpent::set_key(const u4byte in_key[], const u4byte key_len)
{
    u4byte i, lk, a, b, c, d, e, f, g, h;
    u4byte t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16;

    if (/*key_len < 0 ||*/ key_len>256)
        return (u4byte*) 0;

    i  = 0;
    lk = (key_len+31)/32;

    while (i<lk)
    {
#ifdef  BLOCK_SWAP
        l_key[i] = io_swap(in_key[lk-i-1]);
#else
        l_key[i] = in_key[i];
#endif
        i++;
    }

    if (key_len<256)
    {
        while (i<8)

            l_key[i++] = 0;

        i  = key_len/32;
        lk = 1 << key_len%32;

        l_key[i] = (l_key[i] & (lk-1)) | lk;
    }

    for (i = 0; i<132; ++i)
    {
        lk = l_key[i] ^ l_key[i+3] ^ l_key[i+5]
                ^ l_key[i+7] ^ 0x9e3779b9 ^ i;

        l_key[i+8] = (lk << 11) | (lk >> 21);
    }

    k_set(0, a, b, c, d);
    sb3(a, b, c, d, e, f, g, h);
    k_get(0, e, f, g, h);
    k_set(1, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    k_get(1, e, f, g, h);
    k_set(2, a, b, c, d);
    sb1(a, b, c, d, e, f, g, h);
    k_get(2, e, f, g, h);
    k_set(3, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    k_get(3, e, f, g, h);
    k_set(4, a, b, c, d);
    sb7(a, b, c, d, e, f, g, h);
    k_get(4, e, f, g, h);
    k_set(5, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    k_get(5, e, f, g, h);
    k_set(6, a, b, c, d);
    sb5(a, b, c, d, e, f, g, h);
    k_get(6, e, f, g, h);
    k_set(7, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    k_get(7, e, f, g, h);
    k_set(8, a, b, c, d);
    sb3(a, b, c, d, e, f, g, h);
    k_get(8, e, f, g, h);
    k_set(9, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    k_get(9, e, f, g, h);
    k_set(10, a, b, c, d);
    sb1(a, b, c, d, e, f, g, h);
    k_get(10, e, f, g, h);
    k_set(11, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    k_get(11, e, f, g, h);
    k_set(12, a, b, c, d);
    sb7(a, b, c, d, e, f, g, h);
    k_get(12, e, f, g, h);
    k_set(13, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    k_get(13, e, f, g, h);
    k_set(14, a, b, c, d);
    sb5(a, b, c, d, e, f, g, h);
    k_get(14, e, f, g, h);
    k_set(15, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    k_get(15, e, f, g, h);
    k_set(16, a, b, c, d);
    sb3(a, b, c, d, e, f, g, h);
    k_get(16, e, f, g, h);
    k_set(17, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    k_get(17, e, f, g, h);
    k_set(18, a, b, c, d);
    sb1(a, b, c, d, e, f, g, h);
    k_get(18, e, f, g, h);
    k_set(19, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    k_get(19, e, f, g, h);
    k_set(20, a, b, c, d);
    sb7(a, b, c, d, e, f, g, h);
    k_get(20, e, f, g, h);
    k_set(21, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    k_get(21, e, f, g, h);
    k_set(22, a, b, c, d);
    sb5(a, b, c, d, e, f, g, h);
    k_get(22, e, f, g, h);
    k_set(23, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    k_get(23, e, f, g, h);
    k_set(24, a, b, c, d);
    sb3(a, b, c, d, e, f, g, h);
    k_get(24, e, f, g, h);
    k_set(25, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    k_get(25, e, f, g, h);
    k_set(26, a, b, c, d);
    sb1(a, b, c, d, e, f, g, h);
    k_get(26, e, f, g, h);
    k_set(27, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    k_get(27, e, f, g, h);
    k_set(28, a, b, c, d);
    sb7(a, b, c, d, e, f, g, h);
    k_get(28, e, f, g, h);
    k_set(29, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    k_get(29, e, f, g, h);
    k_set(30, a, b, c, d);
    sb5(a, b, c, d, e, f, g, h);
    k_get(30, e, f, g, h);
    k_set(31, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    k_get(31, e, f, g, h);
    k_set(32, a, b, c, d);
    sb3(a, b, c, d, e, f, g, h);
    k_get(32, e, f, g, h);

    return l_key;
};

/* encrypt a block of text  */

void CSerpent::encrypt(const u4byte in_blk[4], u4byte out_blk[])
{
    u4byte a, b, c, d, e, f, g, h;
    u4byte t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16;

#ifdef  BLOCK_SWAP
    a = io_swap(in_blk[3]);
    b = io_swap(in_blk[2]);
    c = io_swap(in_blk[1]);
    d = io_swap(in_blk[0]);
#else
    a = in_blk[0]; b = in_blk[1]; c = in_blk[2]; d = in_blk[3];
#endif

    k_xor(0, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(1, e, f, g, h);
    sb1(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(2, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(3, e, f, g, h);
    sb3(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(4, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(5, e, f, g, h);
    sb5(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(6, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(7, e, f, g, h);
    sb7(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(8, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(9, e, f, g, h);
    sb1(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(10, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(11, e, f, g, h);
    sb3(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(12, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(13, e, f, g, h);
    sb5(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(14, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(15, e, f, g, h);
    sb7(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(16, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(17, e, f, g, h);
    sb1(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(18, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(19, e, f, g, h);
    sb3(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(20, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(21, e, f, g, h);
    sb5(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(22, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(23, e, f, g, h);
    sb7(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(24, a, b, c, d);
    sb0(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(25, e, f, g, h);
    sb1(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(26, a, b, c, d);
    sb2(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(27, e, f, g, h);
    sb3(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(28, a, b, c, d);
    sb4(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(29, e, f, g, h);
    sb5(e, f, g, h, a, b, c, d);
    rot(a, b, c, d);
    k_xor(30, a, b, c, d);
    sb6(a, b, c, d, e, f, g, h);
    rot(e, f, g, h);
    k_xor(31, e, f, g, h);
    sb7(e, f, g, h, a, b, c, d);
    k_xor(32, a, b, c, d);

#ifdef  BLOCK_SWAP
    out_blk[3] = io_swap(a);
    out_blk[2] = io_swap(b);
    out_blk[1] = io_swap(c);
    out_blk[0] = io_swap(d);
#else
    out_blk[0] = a; out_blk[1] = b; out_blk[2] = c; out_blk[3] = d;
#endif
};

/* decrypt a block of text  */

void CSerpent::decrypt(const u4byte in_blk[4], u4byte out_blk[4])
{
    u4byte a, b, c, d, e, f, g, h;
    u4byte t1, t2, t3, t4, t5, t6, t7, t8, t9, t10, t11, t12, t13, t14, t15, t16;

#ifdef  BLOCK_SWAP
    a = io_swap(in_blk[3]);
    b = io_swap(in_blk[2]);
    c = io_swap(in_blk[1]);
    d = io_swap(in_blk[0]);
#else
    a = in_blk[0]; b = in_blk[1]; c = in_blk[2]; d = in_blk[3];
#endif

    k_xor(32, a, b, c, d);
    ib7(a, b, c, d, e, f, g, h);
    k_xor(31, e, f, g, h);
    irot(e, f, g, h);
    ib6(e, f, g, h, a, b, c, d);
    k_xor(30, a, b, c, d);
    irot(a, b, c, d);
    ib5(a, b, c, d, e, f, g, h);
    k_xor(29, e, f, g, h);
    irot(e, f, g, h);
    ib4(e, f, g, h, a, b, c, d);
    k_xor(28, a, b, c, d);
    irot(a, b, c, d);
    ib3(a, b, c, d, e, f, g, h);
    k_xor(27, e, f, g, h);
    irot(e, f, g, h);
    ib2(e, f, g, h, a, b, c, d);
    k_xor(26, a, b, c, d);
    irot(a, b, c, d);
    ib1(a, b, c, d, e, f, g, h);
    k_xor(25, e, f, g, h);
    irot(e, f, g, h);
    ib0(e, f, g, h, a, b, c, d);
    k_xor(24, a, b, c, d);
    irot(a, b, c, d);
    ib7(a, b, c, d, e, f, g, h);
    k_xor(23, e, f, g, h);
    irot(e, f, g, h);
    ib6(e, f, g, h, a, b, c, d);
    k_xor(22, a, b, c, d);
    irot(a, b, c, d);
    ib5(a, b, c, d, e, f, g, h);
    k_xor(21, e, f, g, h);
    irot(e, f, g, h);
    ib4(e, f, g, h, a, b, c, d);
    k_xor(20, a, b, c, d);
    irot(a, b, c, d);
    ib3(a, b, c, d, e, f, g, h);
    k_xor(19, e, f, g, h);
    irot(e, f, g, h);
    ib2(e, f, g, h, a, b, c, d);
    k_xor(18, a, b, c, d);
    irot(a, b, c, d);
    ib1(a, b, c, d, e, f, g, h);
    k_xor(17, e, f, g, h);
    irot(e, f, g, h);
    ib0(e, f, g, h, a, b, c, d);
    k_xor(16, a, b, c, d);
    irot(a, b, c, d);
    ib7(a, b, c, d, e, f, g, h);
    k_xor(15, e, f, g, h);
    irot(e, f, g, h);
    ib6(e, f, g, h, a, b, c, d);
    k_xor(14, a, b, c, d);
    irot(a, b, c, d);
    ib5(a, b, c, d, e, f, g, h);
    k_xor(13, e, f, g, h);
    irot(e, f, g, h);
    ib4(e, f, g, h, a, b, c, d);
    k_xor(12, a, b, c, d);
    irot(a, b, c, d);
    ib3(a, b, c, d, e, f, g, h);
    k_xor(11, e, f, g, h);
    irot(e, f, g, h);
    ib2(e, f, g, h, a, b, c, d);
    k_xor(10, a, b, c, d);
    irot(a, b, c, d);
    ib1(a, b, c, d, e, f, g, h);
    k_xor(9, e, f, g, h);
    irot(e, f, g, h);
    ib0(e, f, g, h, a, b, c, d);
    k_xor(8, a, b, c, d);
    irot(a, b, c, d);
    ib7(a, b, c, d, e, f, g, h);
    k_xor(7, e, f, g, h);
    irot(e, f, g, h);
    ib6(e, f, g, h, a, b, c, d);
    k_xor(6, a, b, c, d);
    irot(a, b, c, d);
    ib5(a, b, c, d, e, f, g, h);
    k_xor(5, e, f, g, h);
    irot(e, f, g, h);
    ib4(e, f, g, h, a, b, c, d);
    k_xor(4, a, b, c, d);
    irot(a, b, c, d);
    ib3(a, b, c, d, e, f, g, h);
    k_xor(3, e, f, g, h);
    irot(e, f, g, h);
    ib2(e, f, g, h, a, b, c, d);
    k_xor(2, a, b, c, d);
    irot(a, b, c, d);
    ib1(a, b, c, d, e, f, g, h);
    k_xor(1, e, f, g, h);
    irot(e, f, g, h);
    ib0(e, f, g, h, a, b, c, d);
    k_xor(0, a, b, c, d);

#ifdef  BLOCK_SWAP
    out_blk[3] = io_swap(a);
    out_blk[2] = io_swap(b);
    out_blk[1] = io_swap(c);
    out_blk[0] = io_swap(d);
#else
    out_blk[0] = a; out_blk[1] = b; out_blk[2] = c; out_blk[3] = d;
#endif
};


